The present invention relates to a stud for a shoe, and a shoe using the studs, and more specifically, to a stud for a shoe, light in weight, and having not only an excellent non-skid performance or gripping performance but also an excellent walking performance on a hard surface of a road such as a pavement, a concrete road, and so forth, or on a hard floor, suitable, particularly, for use in sports shoes such as golf shoes, soccer shoes, or baseball shoes, spikes, non-skid shoes for use in cold districts, and so forth, and a shoe using the same.
Studs for shoes, for example, spikes, especially, spikes for use in sports shoes and non-skid shoes, are required to have excellent gripping performance and nonskid performance, and such performances are important from the viewpoint of providing comfortableness in wearing and safety as well.
As a constituent material of such studs, for example, spikes, and so forth, use is made of a corrosion resistant steel such as stainless steel and carbon steel, a metallic material such as titanium, and so forth, and a hard resin.
The metallic material is superior in strength, but, however, is also too hard as the constituent material of the studs to avoid impact resistance such as a feeling of a thrust coming up from below when a user is walking on a hard surface of a pavement or a concrete road, thereby aggravating the discomfort of the user. In addition, there are also problems that a steel-based material used in the studs renders the shoes heavier because of its high specific gravity while titanium is costly. Further, there is a problem with the hard resin that it has poor abrasion resistance and a short durability.
It is an object of the invention to overcome such drawbacks of the conventional studs as described above, and to provide a stud for a shoe, light in weight, having a long service life and excellent abrasion resistance, and a shoe using the same.
An RB ceramic for use in carrying out an embodiment of a stud according to the invention is a carbonaceous material obtained by utilizing rice bran, produced in a quantity of 900,000 tons a year in Japan and in a quantity of as much as 33 million tons a year throughout the world, and has been well known by researches carried out by Mr. Kazuo Hokkirigawa, the first inventor of the present invention (refer to xe2x80x9cFunctional Materialxe2x80x9d, May issue, 1997, Vol. 17, No. 5, pp. 24-28).
In this literature, reference is made to a carbon material (hereinafter referred to as an RB ceramic) and the preparation thereof, in which the carbonaceous material is obtained by mixing and kneading defatted bran derived from rice bran with a thermosetting resin before kneading, followed by drying a compact obtained by pressure forming a kneaded mixture, and subsequently, baking the dried compact as dried in an atmosphere of an inert gas.
The RB ceramic and a new ceramic (a CRB ceramic as described later on) representing an improvement on the RB ceramic, for use in an embodiment of a stud according to the invention, are ceramic materials friendly to nature, obtained by using rice bran as a raw material, and by mixing defatted bran derived from the rice bran with a thermosetting resin before baking a mixture. These materials have excellent properties as described below:
Higher hardness
Smaller expansion coefficient
porous micro structure
good electrical conductivity
small specific gravity and light weight
very small friction coefficient
excellent abrasion resistance
easy to form and easy to fabricate in a die
ceramics materials having varying characteristics can be produced by blending with various kinds of resins
the materials being made of rice bran, they have little adverse effect on global environment, leading to conservation of natural resources.
The new ceramic described above is an improved material of the RS ceramic, and is a class of ceramic (referred to as the CRB ceramic) that is obtained by mixing defatted bran derived from rice bran with a thermosetting resin. More particularly, the defatted bran derived from rice bran and a thermosetting resin are mixed and kneaded, subjecting a kneaded mixture thus obtained to a primary baking in an inert gas at a temperature-in a range of 700 to 1000xc2x0 C., and pulverizing the kneaded mixture after the primary baking into carbonized powders passing through a 100-mesh sieve.
The carburized powders and the thermosetting resin are further mixed and kneaded, pressure forming a kneaded mixture into a compact at a pressure in a range of 20 to 30 MPa, and subjecting the compact again to a heat treatment in an inert gas atmosphere at a temperature in a range of 100 to, 1100xc2x0 C. The CRB ceramic differs largely from the RB ceramic in that, in contrast with the RB ceramic having a contraction ratio of the dimensions of the compact obtained by pressure forming to those of a finished compact at as high as 25%, the CRB ceramic has a contraction ratio in the order of not more than 3%, which is very small.
The inventors have discovered that these ceramic materials are light in weight and have a long service life, excellent abrasion resistance, insusceptibility to damage, and excellent workability, so that the same are suitable as a constituent material of a stud, for use in combination with a metallic material. The invention has been developed based on such knowledge as described above.
More specifically, the embodiment of the stud according to the invention comprises a central protruding member 1, a seating plate 2, and peripheral binding members 3, wherein the central protruding member 1 and the seating plate 2 are formed of a metallic material, respectively, and the peripheral binding members 3 are formed of the RB ceramic or the CRB ceramic.
Further, with a stud according to another embodiment of the invention, the central protruding member 1 and the peripheral binding members 3 may be formed of the RB ceramic or the CRB ceramic.
Furthermore, the invention provides a shoe using these studs for a shoe.